Abstract. In this paper, we consider the problem of mean-variance hedging in an incomplete market where the underlying assets are jump diffusion processes which are driven by Brownian motion and doubly stochastic Poisson processes. This problem is formulated as a stochastic control problem, and closed form expressions for the optimal hedging policy are obtained using methods from stochastic control and the theory of backward stochastic differential equations. The results we have obtained show how backward stochastic differential equations can be used to obtain solutions to optimal investment and hedging problems when discontinuities in the underlying price processes are modeled by the arrivals of Poisson processes with stochastic intensities. Applications to the problem of hedging default risk are also discussed. 1. Introduction. Much of the literature on asset price modeling is motivated by the observation that simple models, like Black-Scholes, fail to account for important features of price processes that are observed in data. For example, the log-returns process of real-world asset prices are not normally distributed but exhibit higher peaks and heavier tails, implying a greater probability of extreme price movements than predicted by Black-Scholes. In addition, the price processes of real-world assets are typically not continuous, but may jump (in a nonpredictable way) in response to news or other surprise events. For a number of years, researchers have focused on developing a richer class of asset price models that include jumps as well as stochastic parameters; see, for example, [3,12,20]. While the adoption of these models in asset pricing (where simulation can be used) is fairly widespread, their use in dynamic optimization problems like hedging and optimal investment, when the market is incomplete, has been quite limited. This paper is concerned with the problem of dynamic mean-variance hedging in an incomplete market when there are random parameters and discontinuities in the price processes. We assume that uncertainty is modeled by Brownian motion and a doubly stochastic Poisson process with intensity that is predictable with respect to the Brownian filtration. We derive expressions for the optimal hedging strategy using methods from stochastic control and the theory of backward stochastic differential equations (BSDEs).While the theory of BSDEs has played an important role in the analysis and solution of mean-variance hedging problems with random parameters (see [25,27]), it is typically assumed that price processes are continuous and driven by Brownian motion. (We note, however, that generalizations to the continuous semimartingale setting have recently appeared; see Bobrovnytska and Schweizer [6].) One contribution of this paper is to show how BSDEs can be used when there are jumps. In this regard,